In a vehicle equipped with an electric power steering (“EPS”) system, for example, the steering assist torque is provided by an electric motor that is typically coupled to a steering column or shaft. A steering or hand-wheel is also typically coupled to the steering column or shaft in order for a driver to steer the vehicle. When the driver wants to travel substantially straight ahead, the hand-wheel is rotated to a generally centered neutral position having a neutral effect on the direction of travel. However, due to mechanical tolerances and other conditions, the hand-wheel may need to be rotated a small amount away from center to steer the vehicle substantially straight ahead.
Under such off-center conditions, the driver may or may not need to provide any input torque in order to keep the hand-wheel at this neutral position, depending on whether there is any torque coming from the steering system that tends to rotate the hand-wheel clockwise or counter-clockwise. In the cases where the hand-wheel is pulled slightly in one direction, the driver must exert some force to prevent the vehicle from deviating from the intended path. This phenomenon is commonly known as “steering-pull”, which can be caused by many factors such as, for example, tire properties of ply steer or conicity, camber or caster misalignment at the front end, prevailing wind, and road surface or crown.